Java生成随机验证码

package com.tg.snail.core.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.apache.log4j.Logger;
import org.springframework.util.StringUtils;

/**
 * 验证码生成工具类
 * @author penghy
 * @date 2014-02-27
 */
public abstract class RandomCodeUtils {

	private static Logger logger = Logger.getLogger(RandomCodeUtils.class);
	
	private static final String RANDOM_CODE_KEY = "random"; //验证码放在session中的key
	
	private static final int CODE_NUM = 4; //验证码字符个数
	
	// 设置图形验证码中字符串的字体和大小  
	private static Font myFont = new Font("Arial", Font.BOLD, 16);   
  
	//随机字符数组
	private static char[] charSequence = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".toCharArray();
	    
	private static Random random = new Random();
	
	
	/**
	 * 生成随机验证码
	 * @param request
	 * @param response
	 */
	public static void createRandomCode(HttpServletRequest request, HttpServletResponse response){
		// 阻止生成的页面内容被缓存，保证每次重新生成随机验证码  
        response.setHeader("Pragma", "No-cache");  
        response.setHeader("Cache-Control", "no-cache");  
        response.setDateHeader("Expires", 0);  
        response.setContentType("image/jpeg");  
        // 指定图形验证码图片的大小  
        int width = 80, height = 25;  
        // 生成一张新图片  
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);  
        // 在图片中绘制内容  
        Graphics g = image.getGraphics();   
        g.setColor(getRandomColor(200, 250));  
        g.fillRect(1, 1, width - 1, height - 1);  
        g.setColor(new Color(102, 102, 102));  
        g.drawRect(0, 0, width - 1, height - 1);  
        g.setFont(myFont);  
        // 随机生成线条，让图片看起来更加杂乱  
        g.setColor(getRandomColor(160, 200));  
        for (int i = 0; i < 155; i++) {  
            int x = random.nextInt(width - 1);// 起点的x坐标  
            int y = random.nextInt(height - 1);// 起点的y坐标  
            int x1 = random.nextInt(6) + 1;// x轴偏移量  
            int y1 = random.nextInt(12) + 1;// y轴偏移量  
            g.drawLine(x, y, x + x1, y + y1);  
        }  
        // 随机生成线条，让图片看起来更加杂乱  
        for (int i = 0; i < 70; i++) {  
            int x = random.nextInt(width - 1);  
            int y = random.nextInt(height - 1);  
            int x1 = random.nextInt(12) + 1;  
            int y1 = random.nextInt(6) + 1;  
            g.drawLine(x, y, x - x1, y - y1);  
        }  
  
        // 该变量用来保存系统生成的随机字符串  
        StringBuilder sRand = new StringBuilder(CODE_NUM);  
        for (int i = 0; i < CODE_NUM; i++) {  
            // 取得一个随机字符  
            String tmp = getRandomChar();  
            sRand.append(tmp);
            // 将系统生成的随机字符添加到图形验证码图片上  
            g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));  
            g.drawString(tmp, 15 * i + 10, 20);  
        }  
  
        // 取得用户Session  
        HttpSession session = request.getSession(true);  
        // 将系统生成的图形验证码添加  
        session.setAttribute(RANDOM_CODE_KEY, sRand.toString());  
        g.dispose();  
        // 输出图形验证码图片  
        try {
			ImageIO.write(image, "JPEG", response.getOutputStream());
		} catch (IOException e) {
			e.printStackTrace();
		}  
  
	}
	
	/**
	 * 检查用户输入的验证码是否正确
	 * @param request
	 * @param inputCode
	 * @return true: 正确, false:不正确
	 */
	public static boolean checkRandomCode(HttpServletRequest request, String inputCode){
		HttpSession session = request.getSession(false);
		if(session != null && StringUtils.hasLength(inputCode)){
			String code = (String) session.getAttribute(RANDOM_CODE_KEY);
			logger.info("inputCode:"+inputCode.trim()+",code:"+code);
			return inputCode.trim().equalsIgnoreCase(code);
		}
		return false;
	}
	
	/**
	 * 移除验证码
	 * @param request
	 * @param inputCode
	 */
	public static void removeRandomCode(HttpServletRequest request){
		HttpSession session = request.getSession(false);
		if(session != null){
		   session.removeAttribute(RANDOM_CODE_KEY);
		}
	}
	
    // 生成随机颜色  
    private static Color getRandomColor(int fc, int bc) {  
	    Random random = new Random();  
	    if (fc > 255)  
	        fc = 255;  
	    if (bc > 255)  
	        bc = 255;  
	    int r = fc + random.nextInt(bc - fc);  
	    int g = fc + random.nextInt(bc - fc);  
	    int b = fc + random.nextInt(bc - fc);  
	    return new Color(r, g, b);  
    }  
    
    // 随机生成一个字符  
    private static String getRandomChar() {  
    	int index = random.nextInt(charSequence.length);
   	    return String.valueOf(charSequence[index]);
    }
}